The internet is a "fantastic playground for paedophiles" according to an expert at an international conference on the sexual exploitation of children.

Nigel Williams of the British organisation Childnet International told delegates in the Japanese city of Yokohama that the internet offered paedophiles "an excellent opportunity to exchange pornographic material."

[Paedophiles] can remain anonymous [on the internet] and have lots of contacts with children

Nigel Williams

He said pornography could easily be distributed, sometimes to children in order to "sexualise" them.

The four-day meeting aims to chart progress since the first congress five years ago in Stockholm, when delegates agreed to create national plans of action and build a database of offenders and children at risk.

Children are vulnerable on the internet

One delegate, the director of Save the Children in Canada, said her own daughter had nearly become a victim.

Jeane Elise Parlee said her daughter had run away from home after being befriended in an internet chat room.

"Her internet friend was a 15-year-old boy who told her to come and live with him because they would have a better life together," she said.

"She was about to travel 2,000 miles (3,000km) to join him."

Fightback

There has been a massive growth in the use of the internet since the last conference, five years ago in Sweden.

The battle now is for law enforcement agencies to develop the technology to fight back.

One expert, John Carr, of End Child Prostitution in Asian Tourism, said only 20 police forces in the world had the technical capability to tackle cyber-pornography.

He pointed to the success Japan has had in reducing child pornography by introducing stricter laws in 1999. But he admitted many Japanese sites had transferred their operations to Taiwan or South Korea where there are no laws targeting paedophiles on the internet.

Mr Carr said the top countries for producing child pornography for the internet are the USA, Russia, China and Cyprus.